Experimental findings over the past decade promise understanding of the basic biochemical process underlying sleep and the increasingly clear demonstrations of severe sleep disturbances associated with psychiatric disorders, as well as the existence of sleep disorders themselves, indicating need for better means of alleviation. To the extent that the process of sleep can be understood, more effective treatment of disorders of sleep will surely follow. In addition to the clinical, biochemical and endocrinological work this laboratory has done in the past, we are beginning to ask fundamental questions about the nature of sleep, using chemical and psychological probes. These studies contribute to the extensive national and international efforts to understand why we spend one-third of our lives in this state.